Struct rustc_middle::mir::query::ClosureRegionRequirements
source · pub struct ClosureRegionRequirements<'tcx> {
pub num_external_vids: usize,
pub outlives_requirements: Vec<ClosureOutlivesRequirement<'tcx>>,
}
Expand description
After we borrow check a closure, we are left with various requirements that we have inferred between the free regions that appear in the closure’s signature or on its field types. These requirements are then verified and proved by the closure’s creating function. This struct encodes those requirements.
The requirements are listed as being between various RegionVid
. The 0th
region refers to 'static
; subsequent region vids refer to the free
regions that appear in the closure (or generator’s) type, in order of
appearance. (This numbering is actually defined by the UniversalRegions
struct in the NLL region checker. See for example
UniversalRegions::closure_mapping
.) Note the free regions in the
closure’s signature and captures are erased.
Example: If type check produces a closure with the closure substs:
ClosureSubsts = [
'a, // From the parent.
'b,
i8, // the "closure kind"
for<'x> fn(&'<erased> &'x u32) -> &'x u32, // the "closure signature"
&'<erased> String, // some upvar
]
We would “renumber” each free region to a unique vid, as follows:
ClosureSubsts = [
'1, // From the parent.
'2,
i8, // the "closure kind"
for<'x> fn(&'3 &'x u32) -> &'x u32, // the "closure signature"
&'4 String, // some upvar
]
Now the code might impose a requirement like '1: '2
. When an
instance of the closure is created, the corresponding free regions
can be extracted from its type and constrained to have the given
outlives relationship.
In some cases, we have to record outlives requirements between types and
regions as well. In that case, if those types include any regions, those
regions are recorded using their external names (ReStatic
,
ReEarlyBound
, ReFree
). We use these because in a query response we
cannot use ReVar
(which is what we use internally within the rest of the
NLL code).
Fields
num_external_vids: usize
The number of external regions defined on the closure. In our
example above, it would be 3 – one for 'static
, then '1
and '2
. This is just used for a sanity check later on, to
make sure that the number of regions we see at the callsite
matches.
outlives_requirements: Vec<ClosureOutlivesRequirement<'tcx>>
Requirements between the various free regions defined in indices.
Trait Implementations
sourceimpl<'tcx> Clone for ClosureRegionRequirements<'tcx>
impl<'tcx> Clone for ClosureRegionRequirements<'tcx>
sourcefn clone(&self) -> ClosureRegionRequirements<'tcx>
fn clone(&self) -> ClosureRegionRequirements<'tcx>
1.0.0 · sourcefn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read moresourceimpl<'tcx> Debug for ClosureRegionRequirements<'tcx>
impl<'tcx> Debug for ClosureRegionRequirements<'tcx>
sourceimpl<'tcx, __D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<__D> for ClosureRegionRequirements<'tcx>
impl<'tcx, __D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<__D> for ClosureRegionRequirements<'tcx>
sourceimpl<'tcx, __E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<__E> for ClosureRegionRequirements<'tcx>
impl<'tcx, __E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<__E> for ClosureRegionRequirements<'tcx>
sourceimpl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for ClosureRegionRequirements<'tcx>
impl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for ClosureRegionRequirements<'tcx>
fn hash_stable(
&self,
__hcx: &mut StableHashingContext<'__ctx>,
__hasher: &mut StableHasher
)
Auto Trait Implementations
impl<'tcx> !RefUnwindSafe for ClosureRegionRequirements<'tcx>
impl<'tcx> !Send for ClosureRegionRequirements<'tcx>
impl<'tcx> !Sync for ClosureRegionRequirements<'tcx>
impl<'tcx> Unpin for ClosureRegionRequirements<'tcx>
impl<'tcx> !UnwindSafe for ClosureRegionRequirements<'tcx>
Blanket Implementations
sourceimpl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
sourceimpl<Ctxt, T> DepNodeParams<Ctxt> for Twhere
Ctxt: DepContext,
T: for<'a> HashStable<StableHashingContext<'a>> + Debug,
impl<Ctxt, T> DepNodeParams<Ctxt> for Twhere
Ctxt: DepContext,
T: for<'a> HashStable<StableHashingContext<'a>> + Debug,
default fn fingerprint_style() -> FingerprintStyle
sourcedefault fn to_fingerprint(&self, tcx: Ctxt) -> Fingerprint
default fn to_fingerprint(&self, tcx: Ctxt) -> Fingerprint
default fn to_debug_str(&self, Ctxt) -> String
sourcedefault fn recover(Ctxt, &DepNode<<Ctxt as DepContext>::DepKind>) -> Option<T>
default fn recover(Ctxt, &DepNode<<Ctxt as DepContext>::DepKind>) -> Option<T>
DepNode
,
something which is needed when forcing DepNode
s during red-green
evaluation. The query system will only call this method if
fingerprint_style()
is not FingerprintStyle::Opaque
.
It is always valid to return None
here, in which case incremental
compilation will treat the query as having changed instead of forcing it. Read moresourceimpl<T, R> InternIteratorElement<T, R> for T
impl<T, R> InternIteratorElement<T, R> for T
type Output = R
fn intern_with<I, F>(iter: I, f: F) -> <T as InternIteratorElement<T, R>>::Outputwhere
I: Iterator<Item = T>,
F: FnOnce(&[T]) -> R,
sourceimpl<T> MaybeResult<T> for T
impl<T> MaybeResult<T> for T
sourceimpl<CTX, T> Value<CTX> for Twhere
CTX: DepContext,
impl<CTX, T> Value<CTX> for Twhere
CTX: DepContext,
default fn from_cycle_error(tcx: CTX) -> T
impl<'a, T> Captures<'a> for Twhere
T: ?Sized,
Layout
Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...)
attributes. Please see the Rust Reference’s “Type Layout” chapter for details on type layout guarantees.
Size: 32 bytes